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  Printed circuit board and manufacturing method thereofUSPTO Application #: 20070074895Title: Printed circuit board and manufacturing method thereof Abstract: A printed circuit board which is thin and incorporates a large-capacitance capacitor function and a manufacturing method thereof is disclosed. The printed circuit board manufacturing method includes the steps of: forming inner layer conductor circuits 32A on a core substrate 30; forming a recess part 31 on the core substrate 30; housing, in a recess part 31, a planar capacitor device 20 that is not resin molded and has electrodes on the surfaces on a shared side; interposing the same between insulator resin 43 and conductor metal foil 44 to heat pressurize the same for forming a multi-layer plate; forming via holes 41A for electrically connecting an outer layer conductor circuit 42A to the electrodes 21,22 of the capacitor device 20; forming a conductor layer on them; and forming the outer layer conductor circuits 42A on the surfaces of the multi-layer plate. (end of abstract) Agent: Crowell & Moring LLP Intellectual Property Group - Washington, DC, US Inventors: Setsuo Noguchi, Kohtaroh Takahashi, Eiji Matsunaga, Yoshihiko Saiki, Satoshi Arai, Sadamu Toita USPTO Applicaton #: 20070074895 - Class: 174250000 (USPTO) Related Patent Categories: Electricity: Conductors And Insulators, Conduits, Cables Or Conductors, Preformed Panel Circuit Arrangement (e.g., Printed Circuit) The Patent Description & Claims data below is from USPTO Patent Application 20070074895. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a printed circuit board and a manufacturing method thereof. More specifically, the present invention relates to a multi-layer printed circuit board incorporating a capacitor function and a manufacturing method thereof. [0003] 2. Description of Related Art [0004] With the higher performance of electronic equipment, the number of parts mounted on a printed circuit board is being increased. Due to the miniaturization of electronic equipment, the size of the printed circuit board is required to be further reduced. The area on which the parts can be mounted is being made smaller. [0005] With reduction of the parts in size, the density of surface mounting is becoming higher due to microfabrication of the conductor pattern of the printed circuit board. [0006] The increased number of leads of mounted parts, smaller pitch, increased wiring resistance with a higher multi-layer printed circuit board due to a growing number of mounted parts and finer lines, signal delay due to cross talk noise, heat generation, and malfunction of the equipment with these become problems. [0007] To solve these problems, the wiring length of parts need to be reduced. Specifically, there are proposed a method of burying the parts into a printed circuit board as well as of mounting the parts on the surface of the printed circuit board, and a method of incorporating a function equal to that of the parts into a printed circuit board using a high dielectric sheet material having a high dielectric constant and a paste material. Such techniques disclosed in Japanese Published Unexamined Patent Application Nos. 2002-100875 and Hei 6(1994)-69663 are known. [0008] According to the above related art, the formation of a recess part on the printed circuit board to incorporate a smaller chip part thereinto is proposed. At present, the printed circuit board is required to be thinner. Although the chip part is being made smaller, its thickness cannot be sufficiently small, obstructing making the printed circuit board thinner. [0009] The smaller chip reduces the capacitance of a capacitor. It is difficult to respond to a request to make the capacitance larger. SUMMARY OF THE INVENTION [0010] The present invention solves the foregoing problems and provides a printed circuit board which is thin and incorporates a large-capacitance capacitor function and a manufacturing method thereof. [0011] According to the present invention, a capacitor not resin molded is buried into a recess part formed on a core substrate. A large-capacitance capacitor can be incorporated into a thin printed circuit board. [0012] According to the present invention, a printed circuit board manufacturing method includes the steps of: forming inner layer conductor circuits on a core substrate; forming a recess part on the core substrate; housing, in the recess part, a capacitor device not resin molded; forming insulator layers and conductor layers on the core substrate housing the capacitor device to form a multi-layer plate; forming via holes for electrically connecting an outer conductor layer and electrodes of the capacitor device to form a conductor layer thereon; and forming the outer layer conductor circuits on the surfaces of the multi-layer plate. [0013] According to a preferred embodiment, the capacitor device has a planar shape, and anode and cathode electrodes are formed on the surfaces on the shared side. [0014] The size of the recess part is adjusted to be slightly larger than that of the capacitor not resin molded to obtain high part positioning accuracy. The resin for fixing parts do not need to be filled in the recess part, thereby reducing the number of processes. [0015] Preferably, in the printed circuit board, an unmolded and unpackaged capacitor device having a thickness of 300 .mu.m or less is used as a capacitor part to be buried. The unpackaged capacitor device is thinner than the molded chip part. In the case of burying a chip part having the same capacitance, the printed circuit board can be thinner. The printed circuit board having the same thickness can incorporate a large-capacitance capacitor. [0016] Preferably, in the printed circuit board, the capacitor device to be buried in which the electrode portions are subject to copper plating or fixed copper foil having a thickness of 10 to 30 .mu.m and surface roughness is optimized for bonding to the resin is used. The thickness of the electrode portions is 10 to 30 .mu.m. When using a laser for forming via holes for connecting the electrodes to the conductor pattern of an upper layer, the via holes can be formed without damaging the electrodes. The surface roughness of the electrodes is optimized for bonding to the resin. No processes for increasing the bonding to the resin are necessary. The general printed circuit board manufacturing process can be performed from laser beam machining to plating. [0017] Preferably, the electrodes of the buried capacitor device are connected to the conductor pattern of the upper layer by the via holes. When the conductor pattern of the upper layer is an outer layer of the printed circuit board, the surfaces of the via holes filled by electrolytic copper plating or conductive paste are flat. Since their surfaces are flat, no voids are caused in solder used for connection to the parts mounted on the surface of the printed circuit board, enabling high-reliability connection. [0018] According to of the present invention, a capacitor device has a dielectric layer formed on at least one side of a planar metal substrate, an anode electrode formed on the dielectric layer, and a cathode electrode formed via a conductive film on the dielectric layer, wherein the anode electrode and the cathode electrode have a planar structure facing toward the shared side, and resin molding is not given. The capacitor device which is relatively simple in structure and which is preferable for thinning can be easily housed in the recess part of the core substrate to achieve thinning of the multi-layer plate. [0019] According to the present invention, it is possible to obtain a thinner printed circuit board by burying a planar capacitor device not resin molded into a recess part formed on a core substrate. BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIG. 1 is a cross-sectional view showing the structure of a printed circuit board according to an embodiment of the present invention; [0021] FIG. 2 is a cross-sectional view showing the structure of a capacitor device according to an embodiment; Continue reading... Full patent description for Printed circuit board and manufacturing method thereof Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Printed circuit board and manufacturing method thereof patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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